This relates generally to imaging systems and, more particularly, to imaging systems with phase detection capabilities.
Modern electronic devices such as cellular telephones, cameras, and computers often use digital image sensors. Imager sensors (sometimes referred to as imagers) may be formed from a two-dimensional array of image sensing pixels. Each pixel receives incident photons (light) and converts the photons into electrical signals. Image sensors are sometimes designed to provide images to electronic devices using a Joint Photographic Experts Group (JPEG) format.
Some applications such as automatic focusing and three-dimensional (3D) imaging may require electronic devices to provide stereo and/or depth sensing capabilities. For example, to bring an object of interest into focus for an image capture, an electronic device may need to identify the distances between the electronic device and object of interest. To identify distances, conventional electronic devices use complex arrangements. Some arrangements require the use of multiple image sensors and camera lenses that capture images from various viewpoints. Other arrangements require the addition of lenticular arrays that focus incident light on sub-regions of a two-dimensional pixel array. Due to the addition of components such as additional image sensors or complex lens arrays, these arrangements lead to reduced spatial resolution, increased cost, and increased complexity.
Some electronic devices include both image pixels and phase detection pixels in a single image sensor. With this type of arrangement, a camera can use the on-chip phase detection pixels to focus an image without requiring a separate phase detection sensor. However, in some cases the quality of the phase detection data gathered by on-chip phase detection pixels can be negatively affected by both the physical arrangement of the phase detection pixels and characteristics of the targeted scene such as illumination level.
It would therefore be desirable to be able to provide image sensors with improved methods of phase detection.